1. Field of the Invention
The present invention relates to an image connection method for connecting sectional fingerprint images which are continuously picked by a small sensor to each other to generate an entire image, and a program and an apparatus therefor and, more particularly, to an image connection method for extracting characteristic shapes from continuously picked sectional fingerprint images or the like to connect the characteristic shapes, and a program and an apparatus therefor.
2. Description of the Related Arts
In recent years, with achievement of multi-function and high-performance of portable phones and personal digital assistants (PDA) or the like, a lot of important information such as internal consumption information and personal information can be easily carried. For this reason, an electronic device such as a portable phone requires strong security. For example, a device which prevents recorded information from being seen by a person except for a holder of an electronic device is required. At the present, biometrics authentication which uses fingerprints, irises, voiceprints, signatures, and the like for reliably checking holders in place of IDs and passwords has attracted attentions. In the biometrics authentication, unique and individual characters habits are directly detected by a human body in advance and registered in a system. When authentication is to be performed, a unique and individual character or habit is detected and compared with a registered character or habit to identify the person. In the biometrics authentication, since a machine directly observes a human body, theft and falsification are difficult more than in authentication using passwords. Therefore, security higher than that in the authentication using passwords can be maintained.
However, in the biometrics authentication, security higher than that in ID or password authentication can be provided. However, a sensor for detecting a character of a human body is disadvantageously large. For example, in fingerprint authentication, a fingerprint sensor having a size almost equal to that of a fingertip is required. Portable phones and PDAs have been highly integrated and considerably miniaturized. For this reason, a sufficient space for mounting the fingerprint sensor is not left. Therefore, in order to cause a portable phone or a PDA to have a fingerprint recognition function, the fingerprint sensor must be more miniaturized.
For this reason, in order to apply an authentication technique while keeping the same usability as that in a conventional art, a method using a small sensor is proposed. As a conventional individual checking system using a fingerprint sensor, for example, a “fingerprint input apparatus” disclosed in Japanese Unexamined Patent Publication No. 8-263631 is known. In this conventional art, a rotatable cylindrical waveguide is used as a contact medium to a finger of a subject to make a contact portion of the finger of the subject movable, and an entire finger print is input by rotational scanning through an image pickup device. A rotational angle of the cylindrical waveguide at this time is detected by a rotational angle detection means. On the basis of the detected rotational angle, images are connected as a correct fingerprint image by image processing of an image processing means to reconstruct the fingerprint image. The rotational cylindrical waveguide is used as the contact medium to a finger to miniaturize optical components, so that considerable miniaturization is realized.
However, in such a conventional fingerprint input apparatus, a small sensor is used. However, the fingerprint input apparatus measures an amount of movement of a finger, and fingerprint images are connected to each other on the basis of the measurement result. For this reason, a mechanism for detecting an amount of movement of a finger except for a sensor for picking fingerprint images is required, and the miniaturization and cost reduction of the apparatus are not easily realized.
In addition, as another conventional art which does not require a detection mechanism except for a sensor for picking print images, an art disclosed in Japanese Patent No. 2971296 is known. In this conventional art, each line input from a one-dimensional sensor is compared with an image which has been input to extract an amount of character, and similar images are discriminated from each other to be used in checking. However, in a method of picking fingerprint images by using the one-dimensional sensor, when input conditions, i.e., a change in velocity of a finger, horizontal blurring, a difference between an amount of left movement and an amount of right movement, and a curve of a locus change, it is difficult to reconstruct fingerprint images to be input. As a result, checking data which is different from an original amount of character is generated, and a rate of rejecting identical persons at which the fingers of identical persons erroneously rejected increases. When a checking standard is moderated to increase a rate of accepting identical persons, a rate of accepting different persons at which different persons are erroneously recognized as identical persons disadvantageously increases. In addition, input images are compared with other images in units of lines, an amount of calculation increases, and a high-speed process cannot be realized.